Computer based aids for earthmoving machines are becoming more common. For example, systems are being developed which utilize the Global Positioning System (GPS) satellites for determining the position of the machine and even the position of an earthmoving tool. For various reasons, GPS satellites are not always reliable. For example, an obstruction might prevent the GPS receiver from receiving signals from the requisite number of satellites in order to make a position determination.
Thus, such position determining systems typically include one or more additional sensors to aid or improve position determinations. One such sensor is an inertial reference unit (IRU) which typically includes a gyroscope for determining heading.
However, a gyroscope's utility is limited by two inherent characteristics. First, gyroscope readings tend to drift over time up to 10 degrees per hour, making them reliable only for short periods of time. Second, gyroscope readings are affected by temperature. A sudden change in temperature can cause heading drift readings to jump up to 100 degrees per hour.
The present invention is directed to overcoming one or more of the problems identified above.